woody

The front end is the same on M27 49 and 80 so it would suit any of those for someone wanting an original set up. Some later bikes also ended up with the tapered forks as well. At least with that front brake you won't have the problem of chrome peeling off

Re: front tbrake set up - the front end is from an early bike like the M80

From what I can see of it, it looks like the hub used on the Sherpas from 1975/6 M159 up to the last 199b model. Off the top of my head I don't know the diameter. I'm not familiar with Alpinas so don't know what hubs they had, but don't think they used hubs like that. There should be a steel ring plate cover that fits over the spoke ends and is held in place by the sprocket

Not production, someone has added those messing with shock position. The original mounting point is still there with the big headed slot screw. It also has the later type wheel, the 151 had the Pursang type split hub. Nothing wrong with the later wheel of course, smaller and neater hub. Make sure the chrome lining is intact in the hub and check the bearing housing on the brake side as they can wear leaving a loose fitting bearing and if it is slack allowing the bearing to move or 'chatter' a bit, the housing can crack and open up rendering it useless and needing repair

MZ forks

The Haynes manual should give you all of the info you need for your bike as the early 70s 5 speed models are pretty much the same. The bike pictured on the front cover is actually a 151 If you look for another cylinder it has to be from the early 325, models 92, 125 or 151. The cylinder was a new design from 159 onwards and won't interchange with the earlier engines

Yes

The Drayton frames aren't actually that light (they aren't sold as such either) The frame for my C15 is a fair bit heavier than the Faber frame I had before. But standard Bantam frames aren't that heavy either, I've ridden a Bantam with original frame (I don't mean a standard bike, still modified) and the Drayton and there's little in it, Alan Whitton's Cub that I tried a few years ago was around 160/170lbs I think, so a Bantam is going to be very near that taking into account the Cub frame is probably lighter but the engine heavier than the Bantam A sad subject at the moment though as Drayton builder Jim Pickering passed away last night after his battle with cancer. A lovely bloke who will be very much missed in these parts

Not sure if I can explain it any better than I have but whatever colours you find on those frames, you're asking what the original colour was for a 198 and that is silver. Remember how old those frames are, they may have been blasted clean of paint in the past and repainted any colour, and more than once. Originally, the B was white, the A was blue and the rest were silver (excepting the smaller capacity models)

I'm not sure hammerite keys very well to aluminium. I used smoothrite spray on a frame once and it chipped easily, which is the very thing I thought it wasn't supposed to do. If you're looking to paint your frame the original colour, the only Sherpa to have a white frame was the B model 198/199. The 198/199A was bllue, the rest were all silver

The swingarm bolt rusting solid is not an uncommon problem. It's unlikely you'll drive it out, normally the spindle has to be cut through either side of the swingarm which can them be removed, then you can set about removing the spindle

The change to a 39 rear was a strange choice on the A and B models as it makes the gearing quite high compared to earlier bikes. The internal ratios never changed on the 5 speed models, which used 11/46 final drive, until the 199 when 1st to 4th were lowered with the change to 13 teeth on the front. With the A they changed the ratios back to the earlier models, or, depending on what you read or who you believe, changed 2nd to 4th back up to the ratios used on all earlier models, but left 1st as the lower 199 ratio, Whichever, with standard gearing on the A it is running 7 teeth less than earlier models which is a lot although the final drive ratio of 11/39 is the same as the 13/46 of the 199 I haven't ridden a 199 or an A for a very long time so can't remember the feel of the gearing but on my B I run around 43 on the back as 11/39 makes the gearing too high and 1st on the B is the same ratio as the 199. On my 49 and 92 bikes 11/46 makes 1st a bit higher than ideal for tighter going

Yout engine number is JM18301632 so the engine is a 183 from 1976/77, the frame is a 199 only as it doesn't have the A at the end of the number. The 199 and 199A have different frames. It definitely isn't a 1972 bike or engine, the engine and frame number on those begins with a 92 You can check model numbers here http://cemoto.tripod.com/bultaco.htm

The frame is a 1978 350 and the engine is a 350 from two models before, but pretty much the same as the engine that would have been in the frame originally

Add the oil through the small plate with 2 screws on the clutch cover. At the front and at the bottom of the clutch cover is the oil level screw

I use a drop of araldite

From memory, as it's a while since I did one, the toothed cam on the selector has a notch scribed into it which should line up with a dot on the gear behind the 'starfish' wheel, which puts the gearbox in neutral. The notch on the cam is towards the uppermost end Is the 'starfish' the wrong way around, I thought it had a recess on its outward face around the shaft and also may have a dot on it to line up with the notch on the cam when in neutral. I think the long finger top left whose tip is hidden should face rearwards, not forwards. This is all from memory but worth a check which will only take a couple of minutes from where you are now

I've never stopped these things spewing oil other than by blocking the hole. Some will say that causes pressurisation in the fork as air can't escape but I've never had any issues doing this. In the bottom of the fork spring there is a deflector which is presumably to stop oil being sprayed out of the top of the damper rod like a water cannon, these are often missing after numerous rebuilds over the years. Whether they help stop oil being forced up the tube and out of the caps I don't know - possibly...

That's a MAR and they were all 5 speed. Announced in 1971 they didn't go into production until 1972 due to the factory being flooded

MK1 and MK2 were fitted with the same fibreglass tank from the factory, just a different style of green stripe. There are several places that sell repro glass tanks. UK bikes from '73/74 had the original tanks replaced with a UK made alloy tank I forgot that Classic Trial in France also make a UK style alloy tank but it's pretty expensive at over £500

New tank or used? New, Miller used to do a replacement but I guess they're long gone and in Spain, Ossacels sell an alloy tank which is a copy of the UK tank. I don't know of anyone who has bought one of those so haven't heard any reports about quality of fit etc. You can 'open out' the original UK tanks so I guess you could do the same with one of these. Years ago I closed up the gap on my tank which was too wide simply by leaning hard on it with it on the floor (down facing side protected) If it's a used original UK tank it could have been through all sorts of adventures but same as above, you can just open it out which is better than altering the frame lugs and rubbers

The 4 speed was an Ossa Pennine, their first trials bike developed by Mick in 1967/8 and which evolved into the 5 speed MAR in 1971. The 4 speed was available in the US as on the promotional video people are riding them at one of Mick's schools They were dark green with yellow stripes on tank and mudguards, production version looked more like an enduro/scrambles bike than a trials bike I think the official Ossa name was Pluma

Yes the horn goes there although I've never seen one. Probably some of the specialists ion Spain may sell them as they do a lot of original and repro parts. In the UK, no idea apart from being luck on ebay - but the chances of one working if you found one.... This place has a big range of parts http://www.motosdelabuelo.com/

Worth loads of money they are. All the Bultaco engines are essentially the same carcass, just different states of tune and gears to suit their application. The outward appearance changed in early seventies when they went from the round barrel and rounded cases to the square barrel and slimmer cases as fitted on your 175

125 frame probably isn't any smaller or much lighter as the 125 motor still uses full size crankcases. Apart from the twin downtubes, the rest of it looks like a 250 frame from '76 to '78 which used the shorter forks. It even has the bend at the top of the downtubes. I think the only reason the 125 appears to be a smaller bike is the wheels are 20/17 so it sits a bit lower, there is only about an inch or so difference in height between 125 and bigger bikes. The 125 frame was supposedly a prototype for the 250/325 bikes but discarded in favour of continuing with the single downtube (not sure how that would have worked with the side exhaust port unless they were developing a new cylinder) Overall it was prbably a bit lighter but much of that may have come from the smaller top end and possibly a smaller crank assembly A friend of mine had a new 125 and it was truly gutless